March 11, 2009

Rare Dracula Fish Discovered

by ssavage

Researchers from London's Natural History Museum have found a rare fish that features small bone fangs.

Found exclusively in a single Burmese stream, the Danionella dracula appears to have lost its teeth over time before it later evolved the fangs made of bone, researchers said in the Royal Society's journal Proceedings B.

"When you watch them in captivity you can see the males sparring," NHM's Ralf Britz told BBC News.

"They display with their lower jaws open incredibly widely, then they nudge each other; but we don't see any wounds."

Researchers in the UK first witnessed the fish when they were sent in a consignment of aquarium fish.

"After a year or so in captivity they started dying; and when I preserved them and looked at them under the microscope, I thought 'my God, what is this, they can't be teeth'," said Britz.

"And when I looked in more detail, and stained the bone and cartilage with different colors and used an enzyme to dissolve away the muscle, I saw they clearly were not teeth."

Researchers believe the fish lost its teeth some 50 million years ago. Compared to relatives, they appear to reach sexual maturity when their bodies have not fully developed, they told BBC News.

Britz said the discovery is "one of the most extraordinary vertebrates discovered in the last few decades".

"None of the other 3,700 species in the Cypriniform group has any teeth in their jaws. They lost them 50 million years ago. D. dracula however evolved its own tooth-like structures by growing them from the jaw bones rather than re-evolving jaw teeth."

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Image Caption: Images of the head of carp-like fish, Danionella dracula. Unlike the 3700 species in its group, the males have tooth-like structures, shown in the scanning electron micrographs on the right-hand side and in image of the stained fish at top left. Bottom left is female. Courtesy Naturl History Museum